1,587 research outputs found
Features of the synthesis of nanocollo id oxides by laser ablation of bulk metal targets in solutions
Laser ablation of bulk targets in a fluid — a promising new method for the synthesis of "pure" nanocolloids. Nanocrystalline materials produced by laser ablation are widely used in biology, medicine, and catalysis. High local temperature during ablation and large surface area of the particles promote chemical reactions and the formation of a complex composition of nanoparticles. In this paper the characteristics of the process of ablation and the obtaining of nanoparticles in a liquid by laser ablation of active materials (Zn, Ce, Ti, Si) were studied. Ways of increasing the productivity of laser ablation were discussed. Characterization of nanocolloids and nanocrystalline powders were performed. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only
Development of sers substrates based on nanoparticles obtained by pulsed laser ablation
SERS spectroscopy is an effective method for the determination of organic and biological compounds, which finds its place in many areas of human life: the analysis of works of art and food 24 YOUNG SCIENTISTS SESSION SESSION Y products, the identification of drugs and drugs, the study of biological structures, incl. at the cellular level. The creation of simple and effective SERS substrates is an urgent task in the development of this method. This paper presents the results of a study of SERS substrates based on gold nanoparticles (NPs). Gold NPs were obtained by pulsed laser ablation of an Au metal target in alcohol using a Nd:YAG laser (1064 nm, 7 ns, 150 mJ). The resulting colloidal solution was applied onto glass substrates by the drop method, varying the number of layers. The SERS characteristics were studied using a model dye rhodamine 6G using Renishaw inVia Basis Raman microscope. The samples were excited in the region of surface plasmon resonance of gold by laser radiation of 532 nm. The results of the study showed that with an increase in the number of deposited layers up to 5, the intensity of the Raman scattering of the dye increases linearly. With a further increase in the number of layers, the signal saturates. This data correlates with SEM data. At the beginning, an increase in the packing density of NPs in the plane of the substrate is observed. Accordingly, the number of "hot spots" increases, which contribute to the amplification of the signal. Further, the homogeneity of the NP layer deteriorates, and large bulk agglomerates appear. Thus, we have developed a simple method for obtaining SERS substrates, which made it possible to increase the signal intensity up to three orders of magnitude
Structure and optical properties of nanoparticles obtained by pulsed laser ablation of copper in gases
Nano-powders of different composition and structure were obtained by nanosecond pulsed laser ablation (Nd:YAG laser, 7 ns, 1064 nm, 20 Hz, 200 mJ) of a metallic copper target in a simple flow reactor at atmospheric pressure. The crystal structure, nanoparticles’ shape, and surface morphology were shown to depend on the gaseous media used (Air, Ar, N2, CO2). CuO nanopowders with a specific surface area 50 m2/g were synthesized by pulsed laser ablation in carbon dioxide and after annealing in air. The optical properties of the obtained powders were also investigated
Efficiently implementable iterative methods for linear elliptic variational inequalities with constraints on the gradient of solution
© 2015, Allerton Press, Inc. We construct and investigate a new iterative solution method for a finite-dimensional constrained saddle point problem. The results are applied to prove the convergence of different iterativemethods formesh approximations of variational inequalities with constraints on the gradient of solution. In particular, we prove the convergence of two-stage iterative methods. The main advantage of the proposed methods is the simplicity of their implementation. The numerical testing demonstrates high convergence rate of the methods
Metal Oxide Nanoparticle Preparation by Pulsed Laser Ablation of Metallic Targets in Liquid
The basic mechanisms of pulsed laser ablation in liquids (PLAL) as a method for the synthesis of nanoparticles (NPs) were considered. Physical and chemical processes occurring during the PLAL that determine the formation, composition and structure of the nanoparticles obtained are described. The influence of the composition and properties of the target material, the solvent and the characteristics of the laser irradiation on the efficiency of the synthesis of nanoparticles is discussed. Separately, an influence of the absorption and scattering (including nonlinear) of laser radiation in the dispersion of nanoparticles on the primary synthetic processes and secondary transformations inside the colloidal solution is examined. The specificity of the characterization of the colloidal solutions of oxide particles produced by PLAL is highlighted. The most promising practical applications of nanomaterials obtained are identified and the examples of their successful use in catalytic research and biomedicine are provided
Management of non-native tree species in forests of the Alpine space
This guide was prepared within the framework of the project ALPTREES (code ASP791), which is co-funded by the European Commission through the INTERREG Alpine Space financial mechanism. The INTERREG Alpine Space programme is a European transnational cooperation programme for the Alpine region. It provides a framework for facilitating cooperation between key economic, social, and environmental players in seven Alpine countries, as well as between various institutional levels. The programme is financed through the European Regional Development Fund (ERDF) as well as through national public and private co-funding in the Partner States
Visualization of nanoconstructions with DNA-Aptamers for targeted molecules binding on the surface of screen-printed electrodes
Nanoconstructions of gold nanoparticles (NPs) obtained via pulsed laser ablation in liquid with DNA-aptamer specific to protein tumor marker were visualized on the surface of screen-printed electrode using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). AuNPs/aptamer nanoconstuctions distribution on the solid surface was studied. More uniform coverage of the carbon electrode surface with the nanoconstuctions was showed in comparison with DNA-aptamer alone on the golden electrode surface. Targeted binding of the tumor marker molecules with the AuNPs/DNA-aptamer nanoconstuctions was approved
Linear and nonlinear optical properties of trigonal borate crystals K7MIn2-xYbx(B5O10)3 (M = Ca, Sr, Ba; x=0…2) with isolated B5O10 units
Noncentrosymmetric borates K7MIn2−xYbx(B5O10)3 (M = Ca, Sr, Ba; x = 0…2) were synthesized by the solid state reaction and the crystals were successfully grown by the top seeded solution growth method using the K2O-B2O3-MF2 flux. According to Rietveld refinement, the crystal structure belongs to the noncentrosymmetric R32 space group. Also, the octahedrally coordinated In atoms are located at wide ranges ∼8 Å which may be promising for phosphor and laser applications. Samples with ytterbium show a characteristic emission band in the range of 950–1050 nm related to the 2F5/2 → 2F7/2 transition of Yb3+ ions that is commonly used for laser generation. IR, Raman and absorption spectra were obtained for the samples as well. The short cut edge of UV absorption, SHG intensity comparable with KDP and low concentration quenching of luminescence suggest that the K7MIn2−xYbx(B5O10)3 borates are promising self-frequency doubling materials
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